that's where i benefited from working for a couple of years in a motor shop. i learned all about dc motors and how to set them up. i'm happy to hear that there was a wide enough range of adjustment on the brush yoke to accomplish dialing in the reverse operation. some dc motors can't be converted that easily, especially those that have brush geometry that has more of a tilt to the brush mounting.

another good source of motor controllers is from old taylor-dunn electric tugs. they have some excellent motor controllers ranging from 36 vdc to 180 vdc. the newer versions are encapsulated in big extruded heat sinks and the only external components are the isolation, forward and reverse solenoids and the electronic throttle.

you might also consider a ducted, fan forced cooling system for the armature and brushes. heat is a problem for the brushes. when they operate long term at high temps, the carbon gets even more brittle, chips and fractures causing them to develop sharp edges which can scar the copper bus bars on the armature. when the armature wears down, the insulators between the bars start to bounce the brushes causing arcing that further hastens brush and armature wear.

another thing to think about in your evolving design is that the motor will operate at an ambient temperature much higher than the air temp. that tends to condense water from the forced cooling air onto the armature and brushes. dc motors don't deal real well with condensation. it starts to affect commutation and screws with the motor controller.

in that case i would try to fabricate a shroud for the motor to incorporate with the forced air cooling design to allow the heat from the motor to act as a pre-heater for the armature cooling air supply. ideally, you would want to drop 20 or 30 degrees from the ambient motor temperature for the cooling air to the armature end of the motor. if you wanted to get really fancy you could also use a liquid type heat exchanger on the motor frame and a circulation pump to use with the stock heater core for defogging the windshield.

your conversion is really quite elegant and well thought out. i'm following your progress with enthusiasm.

especially those that have brush geometry that has more of a tilt to the brush mounting.

Yeah, we were lucky: the brushes were set vertically off the comm. (Tangentally is probably more correct?)

Quote:

you might also consider a ducted, fan forced cooling system for the armature and brushes. heat is a problem for the brushes. when they operate long term at high temps

In this respect, we may be OK without special cooling considerations. The car's only going to be used for short hops. Its range probably won't be more than about 20 km, and its average trip length will more likely be around like 6 or 7 km (maybe 10 - 15 minutes driving).

Quote:

the motor will operate at an ambient temperature much higher than the air temp. that tends to condense water from the forced cooling air onto the armature and brushes.

Confused. I thought water condenses onto things that are cooler than ambient?

Quote:

your conversion is really quite elegant and well thought out.

It only appears that way because I'm a master of illusion!

The truth is, we've been winging it and not really "reading ahead" to the next step as much as we should be. As proof: 1) we're not using the car we originally planned to use (too rusty). And, 2) we're not using the motor we originally planned to use (diameter too big)! We're just lucky we "happened" to have an extra motor from the forklift that turned out to actually be more appropriate for this car anyway (which I only learned after the fact).

And tonight I couldn't get my eBay golf cart controller to work either . Troubleshooting tomorrow. Each step is pretty much into virgin territory. And to be honest, that's one of the enjoyable things about doing this - learning some new stuff hands on.

the motor will operate at an ambient temperature much higher than the air temp. that tends to condense water from the forced cooling air onto the armature and brushes.

Confused. I thought water condenses onto things that are cooler than ambient?

sorry for that confusion. probably due to my running "flight of thoughts" while i was typing.

the cooler air from forced induction only reduces the temperature of the brush assembly and armature end of the motor with water laden air. the other end of the motor is considerably hotter. that makes the cooler end of the motor generate condensation on the brush yokes and brushes. i used to run into that problem quite often on dc powered drive motors used on industrial extruders. i'd usually "mix" hot air from the motor frame with the cooling air and adjust the combined air to get a temp that provided cooling without forming condensation.

i keep repeating these words to myself whenever i get involved with engineering something - "don't build yourself into a corner."

Got both motor controllers working - the GE EV-1 controller from the forklift, and finally got the Curtis golf cart controller going too.

More correctly, someone who is smarter than I am looked at the wiring diagram I hunted down for the Club Car golf cart and suggested a way to connect the potentiometer using all 3 wires (normally you just have to use 2 pot wires for motor control). The golf cart had a weird 5-wire pot that threw me off. (Hey - 12 months ago, I didn't know what a potentiometer was...)

So! Last night I spun the motor up (and down, and up, and down... ) with the Cursit. So smoooooooooooth. So golf cart-ish. (I should rename this thread: How to make a slow car waaaay slower.) It made me want to pile the batteries on the passenger seat and head for the fairways.

So now the question is: which controller to use in the car (they each have their own advantages/disadvantages). Still, it's a good problem to have.

---

Testing the EV-1 controller:

Above - laid out in the basement on a piece of cardboard is the entire forklift wiring harness and all its connections & switches, attached to the complete control panel on the desk.

The output was fed into a 36v light for testing purposes. The rod I'm pushing rotates the internal pot, which activates the controller, which varies the juice sent to the light ... making this the largest and most complicated dimmer switch I've ever used.

What this means is technically we could put the car back on the ground tonight, hook up some batteries and go drive it around the block. But I may actually restrain myself long enough to mount the potbox in the engine compartment and connect it to the accelerator, rather than control the speed with a dial pot duct-taped to the dashboard!

Lol... i was reading this here thread, but not paying attention to the dates... until i ran out of thread to read. I thought you had stopped working on it, but it's just taking longer than expected. Good luck!

2. Initial press of the go pedal closes the potbox microswitch which brings in the pack positive contactor. The controller is now hot.

3. Pushing the go pedal further moves the potentiometer, which signals the controller, which feeds juice to the motor.

4. Other bits are gauges (amp draw, voltage, hour meter - hey it was on the forklift, why not use it?) and fuses.

5. So there are 2 failsafes if the controller fails "ON" (which is how they fail, apparently full speed ahead): 1) the potentiometer microswitch, and 2) the ignition switch. We're thinking of adding a big red panic button on the dashboard, but haven't decided yet.

---

Breaking news: picked up eight used 6v flooded batts from the local company that sold us the forklift. These are freebies, and they came out of industrial floor cleaners, replaced on a service schedule. They'll make up our test pack. Who knows, maybe they'll have enough life left in them to actually use... still need to test them out.

OK, more pictures. Did some more stuff this weekend considered photo-worthy.

(Clicky, zoomy.)

Potbox installed in the car (well, "positioned" is more accurate. Needs a few more self-tapping bolts to call it "installed"). As luck would have it, the ICE's throttle cable travel very closely matches the travel of the potbox actuator arm. Just needed to back off the throttle stop inside the car a little bit to give the cable the needed full range.

The potbox's actuator arm has physical stops at "off" and "full monty". There's also a second set of stops in the internal mechanism. The return spring is also internal - we'll probably add a second spring on on the actuator arm.

Made cardboard mockups to play around with battery positioning (total box height = battery height including terminals). Hood reinstalled to test for clearance (about 1 1/2 inches - whew - just enough room for racks & cabling). It's like the car was specifically built to accept 4 golf cart batteries up front with an inch or 2 of clearance all around. Nice.

Next step is making battery trays/hold downs. This week my brother and I are going to look at welders (going to split on one). I've never welded before, but there's a first time for everything.

Well, not much to report on actual "progress" of fabricating stuff. We're still officially stuck on the battery rack making step, waiting to get a welder so we can finish building & installing them.

Then again, who needs battery racks!

Just for kicks, on Friday we piled 36v worth of batteries inside the car (in the front & rear passenger footwells) hooked them all up and headed out of the garage for the ForkenSwift's first electric test drive:

just a thought but um i have seen on an electric drag car alternators mouted to a go kart style drive pulley on the back wheels. would it be benificial on this project or would the basic auto alternators not produce enough charge? just a thought and it be awesome the more length you could get out of it. good luck man.

Who is online

Users browsing this forum: No registered users and 3 guests

You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum